The present invention relates broadly to devices for handling articles and, more particularly, to an apparatus that is removeably mountable onto a pallet jack for use therewith in lifting, tilting, transporting, and relocating articles, such as stacks of trays, boxes, furniture or the like from one location to another. A motorized truck having the maneuverability of a pallet jack and upon which the apparatus is permanently mounted is also contemplated within the scope of the present invention.
Many different types of material handling devices or trucks are known in the art. Such devices range from a simple hand truck to a more complex fork lift device. A hand truck requires the manual strength of the operator to assist in lifting, tilting, and maneuvering the load, which is supported on the hand truck on a relatively short platen base. Generally, a hand truck and operator are only capable of maneuvering a load of up to several hundred pounds. In contrast, a fork lift device is generally motorized, has a place for the operator to stand or sit, and is capable of lifting and transporting extremely heavy loads weighing up to several thousand pounds or more. In addition, a standard fork lift usually has fairly long and thick forks for lifting, supporting, and maneuvering heavy or bulky loads, such as palletized loads, industrial machines or equipment.
Specialized material handling trucks having capabilities falling somewhere between hand trucks and fork lifts are also known in the art. One example of such a device is shown in Avitan et al., U.S. Pat. No. 5,478,196, which discloses a small truck that is designed for loading, tilting, and transporting two stacks of interlocking bread trays in side-by-side fashion. Although most of the bread industry still uses hand trucks to load and unload stacks of bread trays from a truck trailer, the device in Avitan offers some benefits.
The device disclosed in Avitan, however, has numerous disadvantages, which, as will be seen, are overcome by the apparatus of the present invention. For example, in order to move stacks of bread as disclosed in Avitan, a bread manufacturer only has the option of purchasing the entire apparatus or truck described in the Avitan patent. Since most bread manufacturers own pallet jacks, there is a need to provide a material handling apparatus that can be mounted onto a pallet jack, which obviates the need for purchasing an entirely new transport vehicle upon which an apparatus is permanently mounted. In addition, the truck disclosed in Avitan has the operator facing away from the stacks of bread trays being loaded onto the truck--while this allows the operator to see clearly when driving the loaded truck in a forward direction, it is quite difficult for the operator to see while backing the truck into correct loading and unloading position. Further, the Avitan patent discloses a standard platen (solid or divided) for disposition beneath the stacks of bread trays to be moved. To fit beneath stacks of bread trays, the standard platen must be fairly thin, which tends to bend easily especially after repeated use. Another disadvantage of the Avitan design is having the pivot point of the tiltable upright approximately halfway up the height of the upright. The high pivot point creates at least two problems: first, since the lower half of the tilted stacks must tilt away from the truck, the operator must ensure that there is sufficient space on the other side of the stacks before the load is tilted; second, the high pivot point places the center of gravity of the load further toward the rear of the truck which decreases the stability of the loaded truck during transport. In addition, the Avitan device does not disclose a means or method for maintaining the stacks of bread trays in abutment with or adjacent to the tiltable upright during tilting or transport. In practice, when being tilted, the stacks of trays may actually lean away from the upright. Such leaning not only increases the lateral instability of the load being carried, but also increases the amount of force exerted on the platen during the tilting process, which, in turn, increases the likelihood that the platen will bend. Further, the truck disclosed in Avitan can only carry as many bread trays as will fit, while tilted, through the height of the opening of a truck trailer into which the stacks of bread trays are being loaded or unloaded. Further, the truck in the Avitan patent is limited to the handling of stacks of bread trays. There is no disclosure or suggestion to use the truck to transport other types of articles, such as furniture, boxes, or similar uniformly-shaped articles. Finally, there is no disclosure or suggestion that the truck have the capability of raising and lowering the articles being moved along the height of the upright to allow the articles to be loaded onto or unloaded from a raised platform or stack, nor is there any disclosure or suggestion that the platen or base have the capability of being adjusted in a side to side fashion to allow the base to be properly centered before loading the article or to allow the article to be side shifted relative to the upright after it has been loaded.